Both eyes open.

When the Sun is behind you, you cannot see the dots. You see the post so you have your top pin, but the bottom pins are not distinguishable. I use the nitro sticks during the day just to make sure I can always see the pins. But if the sun is really strong behind you, then the glow sticks are not strong enough.

I bought a Vital Bow Gear Trapper sight since the Matrix was not bright enough when backlit. Well, the VBG is too bright, no matter where the sun is No backlight problems with this one, but I have to put tape around the sight rings to reduce the amount of light the pins gets.